Wind apron for air supported shelters

ABSTRACT

Wind aprons made of flexible material in sheet form are attached to the sidewalls of an air supported shelter and to the ground to stabilize the shelter against the effects of high velocity winds.

United States Patent Albert E. Dietz Birmingham, Ala.

July 29, 1969 Aug. 31,1971

The United States of America as represented by the Secretary of the Army [72] Inventor [21] Appl. No. [22] Filed [45 Patented [73] Assignee [54] WIND APRON FOR AIR SUPPORTED SHELTERS 2 Claims, 4 Drawing Figs.

[52] U.S. Cl ..52/2, 52/84, 52/ 1 73 [51 Int. Cl ..E04g 11/04, E04h 14/00 [50] Fleld of Search .1 52/2, 24,

[5 6] References Cited UNITED STATES PATENTS 2,411,316 11/1946 Capita 52/2 3,042,051 7/1962 Mauldin 52/2 3,170,472 2/1965 Cushmari 52/2 3,277,615 10/1966 Marquez 52/2 Primary Examiner- Frank L. Abbott Assistant Examiner-Sam D. Burke Attorneysl-larry M. Saragovitz, Edward J. Kelly, Herbert Her] and Charles F. Murphy ABSTRACT: Wind aprons made of flexible material in sheet form are attached to the sidewalls of an air supported shelter and to the ground to stabilize the shelter against the effects of high velocity winds.

ATENTEDAUBBl 1971 3,601,934

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WIND APRON FOR AIR SUPPORTED SHELTERS I The invention described herein may be manufactured, used,

and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to air supported tents of the frameless type which are made of lightweight and substantially air impervious material. The lower edges of the sidewalls of such tents are maintained in close contact with the ground by means of cables attached to the sidewalls of the tents near their lower edges and to ground anchors which are embedded in the ground while the main portion of the tent is supported above the ground by means of air pressure maintaining the walls of the tent under tension. Some of these tents are single walled while others are double walled, the air pressure being; maintained in the latter type of tent within cells which when pressurized form archlike supporting members. Double wall tents can be kept open at the ends or may be closed at the ends when desirable. They are, therefore, particularly useful as shelters for large pieces of military equipment. However, the larger the tent, the greater the danger of damage or destruc -tion thereof due to high velocity winds impinging on such tents.

It is, accordingly, an object of the present invention to provide means for making air supported shelters more stable when exposed to high velocity winds than they otherwise would tend to be.

A further object of the invention is to provide means for improving air supported shelters so that high velocity winds will pass in a substantially streamline flow over such shelters without causing them to rock or vibrate severely.

Other objects and advantages will appear from the description of the invention hereinafter and the accompanying drawings wherein:

FIG. 1 is a perspective view of a double wall, air supported tent having wind aprons along each side of the tent attached to the sidewalls thereof and to the ground, in accordance with the invention.

FIG. 2 is a top plan view of the double wall, air supported tent shown in FIG. 1.

FIG. 3 is a cross section of the double wall, air supported tent shown in FIGS. 1 and 2 along the line 3-3 in FIG. 2, showing the streamline flow of air over a tent which has wind aprons attached thereto.

FIG. 4 shows a modified form of the invention in cross section similar to FIG. 3.

As seen in FIG. 1, a double wall, air supported tent generally comprising an elongated substantially semicylindrical structure the walls of which are formed of archlike tubular cells 11 made of air-impervious, coated fabric, the cells being joined together and having interconnecting passages (not shown) so that air pumped into the structure at any point will diffuse throughout the spaces between the inner and outer walls of the double wall structure, is anchored to the ground at a number of points by means of cables 12 running from the sidewalls near the lower edge thereof of the double wall tent to ground anchors represented by'll3, which are inserted in the ground for anchoring purposes.

As seen in FIGS. 1, 2 and 3 ofthe drawing, the air supported tent I0 is provided with wind aprons 14 which are made of flexible material in sheet form and are attached along a first edge 15 of each wind apron to an exterior sidewall of the tent along a first line of attachment 16 located a predetermined distance above the ground and attached along a second edge 17 (opposite said first edge) of each wind apron to the ground by means of ground anchors spaced apart along a second line of attachment 18 along the ground spaced from the exterior sidewall ofthe tent.

Various types of cooperating fastening means, such as D rings and spring closure fasteners, may be employed for attaching the wind apron to the exterior sidewall of the tent and to the ground at the spaced-apart points along the lines of attachment. Since the structures of these fastening means are not a part of the invention, details thereof have been omitted from the figures illustrating the invention. Thus, when the wind apron is attached to the exterior sidewall of the tent and to the ground, as shown in the drawing, it acts as a flexible baffie which is capable of being deflected by the wind, but which produces a substantially streamline flow of air over the tent from one side thereof to the other side, as shown in FIG. 3, the flow lines of the air blowing from left to right over the tent being designated by reference numeral 119. An opening 20 between the end of the wind apron, the sidewall of the tent, and the ground is produced when the wind apron is attached to the sidewall of the tent and the ground.

Since the wind acting on the tent does not always come directly from one side of the tent or the other at a angle with respect to the sidewall of the tent, there is a distinct possibility that the wind may enter one-of the openings 20 formed between the wind apron, the tent sidewall, and the ground. It is, therefore, preferred to provide the wind apron with extensions 21 attached along each side of the wind apron to close openings 20. These extensions are also attached to the exterior sidewalls of the tent and to the ground in a manner similar to the manner of attachment of the wind apron to the tent sidewalls and the ground. The extensions may be permanently affixed to the wind aprons or detachably attached thereto by means of zippers or other fastening means customarily employed for attaching fabric edges together. The extensions are preferably triangularly shaped. One of the sides 22 of an extension is attached to a side edge 23 of the wind apron. A second side 24 of the extension is attached to the exterior sidewall of the tent along a line 25 which runs in an oblique direction from an end of the first line of attachment of the wind apron to the ground and the third side 26 of the extension is attached to the ground, thus closing the opening 20 between the wind apron and the outer surface of the tent and the ground.

when the openings 20 are closed at both ends of the wind apron in the above-described manner, the tent is better able to withstand winds which strike it from directions other than normal to a sidewall as by so-called quarter winds, since the wind is prevented by the extensions from getting under the wind aprons and thereby exerting an abnormal lifting force on the tent.

The net effect of the wind aprons and the extensionsv attached thereto is to create a substantially streamlined flow of air over the outer surfaces of the wind aprons and the tent. Thus, the force of the wind is not applied perpendicularly or broadside with respect to the sidewall of the tent and, therefore, does not cause excessive vibration and rocking of the tent in high winds.

The tent may be further stabilized, as shown in FIG. 4, by attaching the wind apron to the ground by means of tiedown lines 27 which are attached to the ground and to the undersurface 28 of the wind apron at spaced-apart points lying inter mediate between the first line of attachment of the wind apron to the sidewall of the tent and the second line of attachment thereof to the ground. These points of attachment of the tie down lines to the undersurface 28 of the wind apron are preferably about midway between the first and second lines of attachment of the wind apron. This modification tends to reduce apron-induced motion of the tent, especially on the downwind side of the tent. It, therefore, tends to maintain a more nearly streamlined flow of air over the air supported tent and thus contributes to the maintenance of greater stability of the tent.

While it is possible to attach the wind apron to the sidewall of the air supported tent along a line at almost any level above the ground up to the top of the tent, from a practical standpoint it is important to take into consideration the maximum force which the ground anchors holding the air supported tent to the ground will withstand. In general, the higher the line of attachment along which the wind apron is attached to the sidewall of the tent, the greater the stability of the tent against rocking, but also the greater the lift on the tent caused by the action of the wind on the wind apron, hence the greater the forces tending to extract the ground anchors from the ground. Consequently, for practical purposes the wind apron will generally be attached to the sidewall of the air supported tent' is from about 25 to about 65 when the wind apron is substantially taut and is not being acted on by wind.

The wind aprons of the invention may vary in outline shape; for example, they may be trapezoidal, as disclosed above, or rectangular, or of other outline shapes. if they do not carry extensions to close the openings between them and the shelter at the ends of the wind aprons, it has been found that trapezoidal wind aprons having the shorter of the two parallel sides of the trapezoid attached to the sidewall of the shelter and the longer of the two parallel sides attached to the ground are particularly efiective. If two or more sections of double wall air supported shelter are to be connected together at times to obtain a longer shelter, it is preferred to use rectangular wind aprons provided with conventional means for joining them together along their lateral edges in order to extend the wind aprons as the shelter is extended. Snap fasteners, slide fasteners or other means may be employed for joiningthe rectangular wind aprons together. The openings between the wind aprons, the tent sidewalls and the ground can still be closed by means of triangular extensions attached to the extreme ends of the several joined wind aprons and to the tent sidewalls and the ground.

The wind aprons of the present invention impart a marked increase in stability to air supported tents by reducing the tendency of high velocity winds to cause distortion of the sidewalls and rocking motion of the tents. The force of the wind action on the wind apron creates a downward pressure on the air supported tent, reducing the lifting force which, in the absence of the wind apron, would apply a much stronger force to the anchoring system of the tent tending to extract its ground anchor elements from the ground. Consequently, use of the wind aprons of the invention with air supported tents also permits a decrease in the amount of anchoring required for a given size of tent.

l wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.

I claim:

1. The combination of an elongated frameless air supported shelter formed of flexible and substantially air impervious material, said shelter having walls anchored to the ground, and a wind deflecting apron formed of flexible material in sheet form, said wind deflecting apron being attached along a first edge thereof to the outer surface of at least one of said walls along a first line of attachment which is substantially parallel to the ground and spaced from the ground a distance of from about one quarter to about three quarters of the vertical distance from the ground to the top of said shelter and being attached along a second edge thereof to the ground along a second line of attachment spaced from said shelter a distance such that the angle formed between the ground and the wind deflecting apron when said apron is substantially taut and is not being acted on by wind is from about 25 to abdut 65, the lateral edges of said wind deflecting apron being provided with extensions which are substantially triangular in shape and are conformed to be attached to the outer surface of said shelter and to the ground to close the openings between said wind apron and said outer surface of said shelter at each end of said apron whereby said wind deflecting apron provides for a substantially streamlined flow of air over said shelter and stabilizes said shelter in high velocity winds. 1

2. The combination of claim 1, wherein said wind apron is additionally attached to the ground by tiedown lines attached at spaced-apart points to the undersurface of said apron, said points of attachment of said tiedown lines to said wind apron being intermediate between said first line of attachment and said second line of attachment. 

1. The combination of an elongated frameless air supported shelter formed of flexible and substantially air impervious material, said shelter having walls anchored to the ground, and a wind deflecting apron formed of flexible material in sheet form, said wind deflecting apron being attached along a first edge thereof to the outer surface of at least one of said walls along a first line of attachment which is substantially parallel to the ground and spaced from the ground a distance of from about one quarter to about three quarters of the vertical distance from the ground to the top of said shelter and being attached along a second edge thereof to the ground along a second line of attachment spaced from said shelter a distance such that the angle formed between the ground and the wind deflecting apron when said apron is substantially taut and is not being acted on by wind is from about 25* to about 65*, the lateral edges of said wind deflecting apron being provided with extensions which are substantially triangular in shape and are conformed to be attached to the outer surface of said shelter and to the ground to close the openings between said wind apron and said outer surface of said shelter at each end of said apron whereby said wind deflecting apron provides for a substantially streamlined flow of air over said shelter and stabilizes said shelter in high velocity winds.
 2. The combination of claim 1, wherein said wind apron is additionally attached to the ground by tiedown lines attached at spaced-apart points to the undersurface of said apron, said points of attachment of said tiedown lines to said wind apron being intermediate between said first line of attachment and said second line of attachment. 